Pilot-operated valve structure

Abstract

A pilot-operated valve structure for controlling high pressure fluid flow relative to a pair of cylinders, each having an extend port and a retract port. The valve structure has a pair of pilot-operated 3-way valves, each with a poppet valve member and with pilot valve structure including pilot lines directed to the 3-way valves and to the retract ports of the cylinders. The pilot valve has multiple positions including a neutral position whereby pilot pressure may be directed to the 3-way valves for positioning thereof and to the retract ports of the cylinder for holding the pistons in the cylinders retracted or causing retraction of a piston of an extended cylinder. Two alternate positions of the pilot valve cause positioning of one or the other of the 3-way valves to cause extension of the piston in the associated cylinder while the piston in the other cylinder is maintained in retracted position.

I claim: 
     
       1. A pilot-operated double 4-way valve for controlling flow relative to a pair of cylinders each having an extend port and a retract port comprising, a pair of 3-way valves each having an inlet port, a control port connectable to a cylinder extend port, a port to reservoir, a bore and a poppet valve member movable therein, fluid circuit means for connecting said inlet ports to unidirectional flow from a high pressure fluid source, a pair of pilot pistons associated one with each valve member and operable for positioning of the valve member to cause the associated control port to connect to either the inlet port or the reservoir port, a low pressure fluid pilot circuit including a three-position pilot valve intermediate a primary pilot line and separate pilot lines to both of said pilot pistons, said pilot lines also connectable one to each of said cylinder retract ports, and means for positioning said pilot valve either in a first position to connect both pilot lines to said primary pilot line for directing pilot pressure to the pilot pistons and retract ports for positioning a piston in both cylinders in a retract position, in a second position to cause extension of the piston in one cylinder while the piston in the other cylinder remains retracted, or a third position to cause extension of the piston in the other cylinder while the piston in said one cylinder remains retracted. 
     
     
       2. A valve as defined in claim 1 including a fluid supply line with a pressure-reducing valve having a pair of outlets with one outlet connected to said primary pilot line and the other connected to said fluid circuit means. 
     
     
       3. A valve as defined in claim 1 including spring means associated with each valve member to urge the valve member to a position to close said reservoir port, and said pilot pressure acting on a pilot piston to shift the pilot piston and a valve member against the spring means to open said reservoir port and close said inlet port. 
     
     
       4. A pilot-operated double 4-way valve for controlling high pressure flow relative to a pair of cylinders each having an extend port and a retract port comprising, a pair of 3-way valves each having an inlet port, a control port connectable to a cylinder extend port, a port to reservoir, a bore with a pair of spaced-apart valve seats and a poppet valve member movable therein between said pair of valve seats, fluid circuit means for connecting said inlet ports to a high pressure fluid source, a pair of pilot pistons associated one with each valve member and operable for positioning of the valve member against one or the other of the valve seats to cause the associated control port to connect to either the inlet port or the reservoir port, a low pressure fluid pilot circuit including a three-position pilot valve intermediate a primary pilot line and a reservoir line and separate pilot lines to both of said pilot pistons, pilot pressure acting on a pilot piston to cause a valve member to connect a control port to a reservoir port, said pilot lines also connectable one to each of said cylinder retract ports, and means for positioning said pilot valve either in a first position to connect both pilot lines to said primary pilot line for directing pilot pressure to the pilot pistons to close said inlet ports and to the retract ports for positioning a piston in both cylinders in a retract position, in a second position to connect one pilot line to reservoir and cause extension of the piston in the cylinder associated with said one pilot line while the piston in the other cylinder remains retracted, or a third position to connect the other pilot line to reservoir and cause extension of the piston in the cylinder associated with said other pilot line. 
     
     
       5. A valve as defined in claim 4 wherein each of the valve members has a double frusto-conical shape and the diameter of the valve seat between the control port and the reservoir port is greater than the diameter of the valve seat between the control port and the inlet port. 
     
     
       6. A pilot-operated double 4-way valve usable in systems having fluid pressures approximating 10,000 psi for controlling flow relative to a pair of cylinders each having an extend port and a retract port comprising, a pair of 3-way valves each having an inlet port, a control port connectable to a cylinder extend port, a port to reservoir, a bore and a valve member movable therein, fluid circuit means including a pressure-reducing valve for connecting said inlet ports to a high pressure fluid source, a pair of pilot pistons associated one with each valve member and operable for positioning of the valve member to cause the associated control port to connect to either the inlet port or the reservoir port, a low pressure fluid pilot circuit including a three-position 4-way pilot valve having a port to reservoir and intermediate a primary pilot line and separate pilot lines to both of said pilot pistons, said primary pilot line being connected to a low pressure outlet of the pressure-reducing valve, said pilot lines also connectable one to each of said cylinder retract ports, and means for positioning said pilot valve either in a first position to connect both pilot lines to said primary pilot line for directing pilot pressure to the pilot pistons and retract ports for positioning a piston in both cylinders in a retract position, in a second position to connect one pilot line to reservoir and one pilot line to pilot pressure to cause extension of the piston in one cylinder while the piston in the other cylinder remains retracted, or a third position to reverse the last-mentioned connections of the pilot lines to cause extension of the piston in the other cylinder while the piston in said one cylinder remains retracted. 
     
     
       7. A pilot-operated, 4-way valve for controlling high pressure flow relative to a pair of control ports connectable one to a port of each of a pair of double-acting cylinders including; a pair of 3-way valves each having an inlet port, one of said control ports, a port to reservoir, a bore and a valve spool movable therein, a pair of spaced-apart valve seats positioned one between said control port and reservoir port and the other between said control port and the inlet port, and each of said valve spools having a poppet valve member engageable with one or the other of said last-mentioned seats and being balanced relative to pressure in the control port when closed against said other valve seat, a spring urging the poppet valve member toward said one valve seat; a pressure-reducing valve having a fluid supply port and first and second outlet ports with said first outlet port delivering pilot fluid, a valve spool with a poppet valve member for closing against a seat for blocking flow between said supply port and said first outlet port and being balanced relative to pressure in the second outlet port when said poppet valve member is closed; a passage connected to said second outlet port of the pressure-reducing valve and with two branches thereof connected one to each of the inlet ports of the 3-way valves for delivery of fluid to the inlet ports of said 3-way valves; a pair of check valves positioned one in each of said branch passages and blocking return fluid flow from the 3-way valves to the pressure-reducing valve; and a pilot control for said pair of 3-way valves including, a pilot control valve having an inlet connected to the first outlet port of the pressure-reducing valve, an outlet port to reservoir and a pair of outlet ports connected to a pair of pilot lines connected one to each of said pilot pistons, a pair of pilot pistons associated one with each 3-way valve and actuable by pilot fluid to move the valve spool of the associated 3-way valve away from said one seat thereof to connect a control port to reservoir and against said other seat to block said control port from the inlet port whereby fluid may flow through one of said check valves to the other of said 3-way valves which is against said one valve seat and to said control port, and a pair of ports connected one to each of said pilot lines and connectable one to another port of each of said pair of double-acting cylinders.